COS3711 Assignment 1 Semester 1 2026 (Answer Guide)

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COS3711 Assignment 1 Semester 1 2026 (Answer Guide)
VERIFIED AND CERTIFIED ANSWERS. WRITTEN IN REQUIRED FORMAT AND WITHIN
GIVEN GUIDELINES. IT IS GOOD TO USE AS A GUIDE AND FOR REFERENCE, NEVER
PLAGARIZE. Thank you and success in your academics.
UNISA, 2026




QUESTION 1

Object-Oriented Design: Vehicle Management Console Application (Qt)

1.1 Introduction and Design Approach

The objective of this question is to design and implement a Qt-based console
application that manages vehicle details while adhering strictly to object-oriented
programming (OOP) principles. The design avoids common anti-patterns such as
code duplication, tight coupling, and poor encapsulation.

To achieve this:

 Inheritance is used to model shared vehicle characteristics.
 Polymorphism is applied to allow different vehicle types to output their details
appropriately.
 Encapsulation ensures that class attributes are protected and accessed through
getters and setters.
 Qt’s parent–child (QObject) mechanism is used to manage a list of vehicles
safely and efficiently without manual memory management.

1.2 Identification of Required Classes

Based on the specification, the following classes are required:

1. Vehicle – Base class representing common vehicle attributes
2. PassengerVehicle – Derived class for vehicles that carry passengers

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3. TransportVehicle – Derived class for vehicles that carry goods
4. Main application (main.cpp) – Used to test the implementation

1.3 Base Class: Vehicle

1.3.1 Purpose of the Class

The Vehicle class represents the general concept of a vehicle. It contains properties
that are common to all vehicles, namely:

 Model
 Year of manufacture

This class is designed as a QObject-derived class to enable the use of Qt’s parent–
child system.

1.3.2 Attributes

 QString model – Stores the vehicle model
 int year – Stores the year of manufacture

The year value is validated to ensure it is reasonable, meaning:

 It is not earlier than the invention of modern vehicles
 It is not later than the current year

1.3.3 Constructors

 A default constructor assigns safe default values when no information is
provided.
 This satisfies the requirement that vehicles created without necessary details
must still have valid values.

1.3.4 Getters, Setters, and Output Function

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class Vehicle : public QObject {
Q_OBJECT


public:
explicit Vehicle(QObject *parent = nullptr)
: QObject(parent), m_model("Unknown"), m_year(2000) {}


QString getModel() const {
return m_model;
}


void setModel(const QString &model) {
m_model = model;
}


int getYear() const {
return m_year;
}


void setYear(int year) {
if (year >= 1886 && year <= QDate::currentDate().year()) {
m_year = year;
}
}


virtual void printDetails() const {
qDebug() << "Model:" << m_model << ", Year:" << m_year;
}


private:
QString m_model;